This invention relates generally to fibers and the nonwoven fabric or web which is formed from such fibers of a thermoplastic resin, and laminates using such a web as a component.
Thermoplastic resins have been extruded to form fibers, fabrics and webs for a number of years. The most common thermoplastics for this application are polyolefins, particularly polypropylene. Other materials such as polyesters, polyetheresters, polyamides and polyurethanes are also used to form nonwoven fabrics.
Nonwoven fabrics or webs are useful for a wide variety of applications such as diapers, feminine hygiene products, towels, and recreational or protective fabrics. The nonwoven fabrics used in these applications are often in the form of laminates like spunbond/meltblown/spunbond (SMS) laminates. The strength of a nonwoven fabric is one of the most desired characteristics. Higher strength webs allow thinner layers of material to be used to give strength equivalent to a thicker layer, thereby giving the consumer of any product of which the web is a part, a cost, bulk and weight savings. It is also very desirable that such webs, especially when used in consumer products such as diapers or feminine hygiene products, be very soft.
It is an object of this invention to provide a polypropylene nonwoven fabric or web which is very strong and yet is also very soft.